Seismic Provisions for Structural Steel Buildings

333 Pages·2005·5.25 MB·English

ANSI/AISC 341-05
ANSI/AISC 341s1-05
An American National Standard
Seismic Provisions for
Structural Steel Buildings
Including Supplement No. 1
Seismic Provisions for Structural Steel Buildings dated March 9, 2005
and Supplement No. 1 dated November 16, 2005
Supersedes the Seismic Provisions
for Structural Steel Buildings
dated May 21, 2002
and all previous versions
Approved by the
AISC Committee on Specifications and
issued by the AISC Board of Directors
AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
One East Wacker Drive, Suite 700
Chicago, Illinois 60601-1802
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Copyright © 2005
by American Institute of Steel Construction, Inc.
All rights reserved. This book or any part thereof must not be reproduced in any form
without the written permission of the publisher.
The AISC logo is a registered trademark of AISC and is used under license.
The information presented in this publication has been prepared in accordance with
recognized engineering principles and is for general information only. While it is
believed to be accurate, this information should not be used or relied upon for any
specific application without competent professional examination and verification
of its accuracy, suitability, and applicability by a licensed engineer, architect or
other professional. The publication of the material contained herein is not intended
as a representation or warranty on the part of the American Institute of Steel
Construction, Inc., or of any other person named herein, that this information
is suitable for any general or particular use or of freedom from infringement of
any patent or patents. Anyone making use of this information assumes all liability
arising from such use.
Caution must be exercised when relying upon other specifications and codes
developed by other bodies and incorporated by reference herein since such material
may be modified or amended from time to time subsequent to the printing of this
edition. The American Institute of Steel Construction, Inc. bears no responsibility
for such material other than to refer to it and incorporate it by reference at the
time of the initial publication of this edition.
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iii
PREFACE
This Preface is not a part of ANSI/AISC 341-05, Seismic Provisions for Structural Steel
Buildings, but is included for informational purposes only.
The AISC Specification for Structural Steel Buildings (ANSI/AISC 360-05) is intended to
cover common design criteria. Accordingly, it is not feasible for it to also cover all of the
special and unique problems encountered within the full range of structural design practice.
This document, the AISC Seismic Provisions for Structural Steel Buildings (ANSI/AISC 341-
05) with Supplement No. 1 (ANSI/AISC 341s1-05) (hereafter referred to as the Provisions)
is a separate consensus standard that addresses one such topic: the design and construction of
structural steel and composite structural steel/reinforced concrete building systems for high-
seismic applications. Supplement No. 1 consists of modifications made to Part I, Section 14
of the Provisions after the initial approval had been completed.
These Provisions are presented in two parts: Part I is intended for the design and construction
of structural steel buildings, and is written in a unified format that addresses both LRFD
and ASD; Part II is intended for the design and construction of composite structural steel/
reinforced concrete buildings, and is written to address LRFD only. In addition, seven
mandatory appendices, a list of Symbols, and Glossary are part of this document. Terms
that appear in the Glossary are generally italicized where they first appear in a sub-section,
throughout these Provisions. A nonmandatory Commentary with background information is
also provided.
The previous edition of the AISC Seismic Provisions for Structural Steel Buildings,
approved on May 21, 2002, incorporated many of the advances achieved as part of the
FEMA/SAC program and other investigations and developments related to the seismic
design of steel buildings. Recognizing that rapid and significant changes in the knowledge
base were occurring for the seismic design of steel buildings, especially moment frames, the
AISC Committee on Specifications committed to generating frequent supplements to the
Provisions. This commitment was intended to keep the provisions as current as possible.
These Provisions were modified to be consistent with SEI/ASCE 7-05, Minimum Design
Loads for Buildings and Other Structures. Although this standard adopts SEI/ASCE 7-02,
it was being developed in parallel with SEI/ASCE 7-05. It is anticipated that ASCE will
publish a supplement to SEI/ASCE 7-05 in 2006 that will adopt ANSI/AISC 341 and 360
by reference. We encourage anyone who is using these AISC standards to use them in
conjunction with SEI/ASCE 7-05 including Supplement No. 1, when it becomes available.
This allows these Provisions to be incorporated by reference into both the 2006 IBC and
2006 NFPA 5000 building codes, each of which uses SEI/ASCE 7-05 as its basis for design
loadings. Because the extent of changes that have been made to these Provisions, as a result
of incorporating both technical changes and the unified format is so large, they are being
republished in their entirety. The most significant modification is that two systems initially
developed and incorporated into the 2003 NEHRP Provisions, the buckling-restrained braced
frame (BRBF) and the special plate shear wall (SPSW) have been added to the Provisions. A
major update to the commentary is also provided.
A number of other significant technical modifications are included, as follows:
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iv PREFACE
(cid:129) Clarifying that the scope of structures covered includes “building-like nonbuilding
structures.”
(cid:129) Clarifying that all steel buildings designed with an R factor greater than 3 must comply
with the Provisions.
(cid:129) Adding new requirements to delineate the expectations for structural design drawings
and specifications, shop drawings and erection drawings.
(cid:129) Adding new ASTM material specifications that are commonly used in the metal building
industry.
(cid:129) Adding R values for all materials to be used in determining susceptibility of connections
t
to fracture limit states.
(cid:129) Relaxing the limitations on use of oversized holes in bolted joints.
(cid:129) Defining a new term, “demand critical welds,” which have additional quality and
toughness requirements. For each system, welds considered to be demand critical are
defined.
(cid:129) Defining a new term, “protected zone,” to ensure that areas subject to significant
inelastic deformations are not disturbed by other building construction operations. For
each system, what areas are considered to be protected zones are defined.
(cid:129) Expanding the applicability of requirements on splices in columns that are part of the
seismic load resisting system in moment frames to all systems.
(cid:129) Improving the provisions related to the design of column bases.
(cid:129) Making the stability bracing requirements more consistent throughout the document.
(cid:129) Added references to the new AISC Prequalified Connections for Special and
Intermediate Steel Moment Frames for Seismic Applications (ANSI/AISC 358-05) as
one means for SMF, IMF and EBF (link-to-column) connection acceptance.
(cid:129) Decreasing the column splice shear capacity requirements for SMF systems.
(cid:129) Increasing the stability bracing requirements for IMF systems.
(cid:129) Clarifying that connections meeting the requirements for SMF or IMF systems are also
acceptable for OMF applications.
(cid:129) Increasing the requirements on SCBF systems that employ braces with high Kl/r ratios.
(cid:129) Reducing the connection force demand on OCBF bracing to allow the use of the
amplified seismic load.
(cid:129) Eliminating the requirement to design all members in OCBF systems for the amplified
seismic load, done for consistency with a corresponding reduction in the R factor for
this system in SEI/ASCE 7-05 including Supplement 1.
(cid:129) Adding specific requirements for OCBF above seismic isolation systems.
(cid:129) Significantly improving the provisions related to quality assurance and quality control
to address many of the issues identified in FEMA 353.
(cid:129) Making changes to Part II to be consistent with the modifications to Part I and changes
to ACI 318.
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PREFACE v
The AISC Committee on Specifications, Task Committee 9—Seismic Provisions is responsible
for the ongoing development of these Provisions. The AISC Committee on Specifications
gives final approval of the document through an ANSI-accredited balloting process, and
has enhanced these Provisions through careful scrutiny, discussion, and suggestions for
improvement. AISC further acknowledges the significant contributions of several groups
to the completion of this document: the Building Seismic Safety Council (BSSC), the SAC
Joint Venture, the Federal Emergency Management Agency (FEMA), the National Science
Foundation (NSF), and the Structural Engineers Association of California (SEAOC).
The reader is cautioned that professional judgment must be exercised when data or
recommendations in these provisions are applied, as described more fully in the disclaimer
notice preceding the Preface.
This specification was approved by the AISC Committee on Specifications:
James M. Fisher, Chairman Tony C. Hazel
Roger E. Ferch, Vice Chairman Mark V. Holland
Hansraj G. Ashar Lawrence A. Kloiber
William F. Baker Roberto T. Leon
John M. Barsom Stanley D. Lindsey
William D. Bast James O. Malley
Reidar Bjorhovde Richard W. Marshall (deceased)
Roger L. Brockenbrough Harry W. Martin
Gregory G. Deierlein David L. McKenzie
Duane S. Ellifritt Duane K. Miller
Bruce R. Ellingwood Thomas M. Murray
Michael Engelhardt R. Shankar Nair
Shu-Jin Fang Jack E. Petersen
Steven J. Fenves Douglas A. Rees-Evans
John W. Fisher Robert E. Shaw, Jr.
Timothy P. Fraser Donald R. Sherman
Theodore V. Galambos Lee Shoemaker
Louis F. Geschwindner William A. Thornton
Lawrence G. Griffis Raymond H. R. Tide
John L. Gross Cynthia J. Duncan, Secretary
The Committee gratefully acknowledges the following task committee (TC 9—Seismic
Design) for their development of this document.
James O. Malley, Chairman Roberto T. Leon
Mark C. Saunders, Vice Chairman Robert T. Lyons
Roy Becker Sanjeev R. Malushte
Gregory G. Deierlein Harry W. Martin
Richard M. Drake Clarkson W. Pinkham
Michael D. Engelhardt Rafael Sabelli
Roger E. Ferch Thomas A. Sabol
Timothy P. Fraser Robert E. Shaw, Jr.
Subhash C. Goel Kurt D. Swensson
James R. Harris Cynthia J. Duncan, Secretary
Patrick M. Hassett
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TABLE OF CONTENTS
SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
PART I STRUCTURAL STEEL BUILDINGS — PROVISIONS
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
1. SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
2. REFERENCED SPECIFICATIONS, CODES, AND STANDARDS . . . . . . . . 15
3. GENERAL SEISMIC DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . 16
4. LOADS, LOAD COMBINATIONS, AND NOMINAL STRENGTHS . . . . . . 16
4.1. Loads and Load Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.2. Nominal Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5. STRUCTURAL DESIGN DRAWINGS AND SPECIFICATIONS,
SHOP DRAWINGS, AND ERECTION DRAWINGS . . . . . . . . . . . . . . . . . . . 16
5.1. Structural Design Drawings and Specifications . . . . . . . . . . . . . . . . . . . . 17
5.2. Shop Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3. Erection Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6. MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1. Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2. Material Properties for Determination of Required Strength
of Members and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.3. Heavy Section CVN Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7. CONNECTIONS, JOINTS, AND FASTENERS . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2. Bolted Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.3. Welded Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.3a. General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.3b. Demand Critical Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.4. Protected Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.5. Continuity Plates and Stiffeners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8. MEMBERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.2. Classification of Sections for Local Buckling . . . . . . . . . . . . . . . . . . . . . 24
8.2a. Compact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.2b. Seismically Compact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
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8.3. Column Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.4. Column Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.4a. General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.4b. Columns Not Part of the Seismic Load Resisting System . . . . . . . . . . . . 27
8.5. Column Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.5a. Required Axial Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.5b. Required Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.5c. Required Flexural Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.6. H-Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.6a. Design of H-Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.6b. Battered H-Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.6c. Tension in H-Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9. SPECIAL MOMENT FRAMES (SMF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.2. Beam-to-Column Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.2a. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.2b. Conformance Demonstration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
9.2c. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.2d. Protected Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.3. Panel Zone of Beam-to-Column Connections
(beam web parallel to column web) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.3a. Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.3b. Panel Zone Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.3c. Panel Zone Doubler Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.4. Beam and Column Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.4a. Width-Thickness Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.4b. Beam Flanges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.5. Continuity Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.6. Column-Beam Moment Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.7. Lateral Bracing at Beam-to-Column Connections . . . . . . . . . . . . . . . . . 34
9.7a. Braced Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
9.7b. Unbraced Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
9.8. Lateral Bracing of Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
9.9. Column Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10. INTERMEDIATE MOMENT FRAMES (IMF) . . . . . . . . . . . . . . . . . . . . . . . . 36
10.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.2. Beam-to-Column Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.2a. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.2b. Conformance Demonstration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.2c. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10.2d. Protected Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10.3. Panel Zone of Beam-to-Column Connections
(beam web parallel to column web) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10.4. Beam and Column Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
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10.4a. Width-Thickness Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10.4b. Beam Flanges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
10.5. Continuity Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
10.6. Column-Beam Moment Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
10.7. Lateral Bracing at Beam-to-Column Connections . . . . . . . . . . . . . . . . . 38
10.8. Lateral Bracing of Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
10.9. Column Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
11. ORDINARY MOMENT FRAMES (OMF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
11.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
11.2. Beam-to-Column Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
11.2a. Requirements for FR Moment Connections . . . . . . . . . . . . . . . . . . . . . . . 39
11.2b. Requirements for PR Moment Connections . . . . . . . . . . . . . . . . . . . . . . . 41
11.2c. Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
11.3. Panel Zone of Beam-to-Column Connections
(beam web parallel to column web) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
11.4. Beam and Column Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
11.5. Continuity Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
11.6. Column-Beam Moment Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
11.7. Lateral Bracing at Beam-to-Column Connections . . . . . . . . . . . . . . . . . . 42
11.8. Lateral Bracing of Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
11.9. Column Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
12. SPECIAL TRUSS MOMENT FRAMES (STMF) . . . . . . . . . . . . . . . . . . . . . . 42
12.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
12.2. Special Segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
12.3. Strength of Special Segment Members . . . . . . . . . . . . . . . . . . . . . . . . . . 43
12.4. Strength of Non-Special Segment Members . . . . . . . . . . . . . . . . . . . . . . 43
12.5. Width-Thickness Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
12.6. Lateral Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
13. SPECIAL CONCENTRICALLY BRACED FRAMES (SCBF) . . . . . . . . . . . 44
13.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
13.2. Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
13.2a. Slenderness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
13.2b. Required Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
13.2c. Lateral Force Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
13.2d. Width-Thickness Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
13.2e. Built-up Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
13.3. Required Strength of Bracing Connections . . . . . . . . . . . . . . . . . . . . . . . 46
13.3a. Required Tensile Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
13.3b. Required Flexural Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
13.3c. Required Compressive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
13.4. Special Bracing Configuration Requirements . . . . . . . . . . . . . . . . . . . . . 47
13.4a. V-Type and Inverted V-Type Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
13.4b. K-Type Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1
AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
SSeeiissmmiiccPPrroovv11..iinndddd iixx 1111//2288//0055 33::4444::5588 PPMM
PPrroocceessss BBllaacckk
x TABLE OF CONTENTS
13.5. Column Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
13.6. Protected Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
14. ORDINARY CONCENTRICALLY BRACED FRAMES (OCBF) . . . . . . . . . 48
14.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
14.2. Bracing Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
14.3. Special Bracing Configuration Requirements . . . . . . . . . . . . . . . . . . . . . 48
14.4. Bracing Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
14.5. OCBF above Seismic Isolation Systems . . . . . . . . . . . . . . . . . . . . . . . . . 49
14.5a. Bracing Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
14.5b. K-Type Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
14.5c. V-Type and Inverted-V-Type Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
15. ECCENTRICALLY BRACED FRAMES (EBF) . . . . . . . . . . . . . . . . . . . . . . . 50
15.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
15.2. Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
15.2a. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
15.2b. Shear Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
15.2c. Link Rotation Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
15.3. Link Stiffeners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
15.4. Link-to-Column Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
15.5. Lateral Bracing of Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
15.6. Diagonal Brace and Beam Outside of Link . . . . . . . . . . . . . . . . . . . . . . . 53
15.6a. Diagonal Brace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
15.6b. Beam Outside Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
15.6c. Bracing Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
15.7. Beam-to-Column Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
15.8. Required Strength of Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
15.9. Protected Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
15.10. Demand Critical Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
16. BUCKLING-RESTRAINED BRACED FRAMES (BRBF) . . . . . . . . . . . . . . . 55
16.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
16.2. Bracing Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
16.2a. Steel Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
16.2b. Buckling-Restraining System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
16.2c. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
16.2d. Adjusted Brace Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
16.3. Bracing Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
16.3a. Required Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
16.3b. Gusset Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
16.4. Special Requirements Related to Bracing Configuration . . . . . . . . . . . . . 57
16.5. Beams and Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
16.5a. Width-Thickness Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
16.5b. Required Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
16.5c. Splices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
16.6. Protected Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1
AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
SSeeiissmmiiccPPrroovv11..iinndddd xx 1111//2288//0055 33::4444::5588 PPMM
PPrroocceessss BBllaacckk